Magnetically actuated pump

ABSTRACT

A pump for pumping one or more media comprises a housing ( 1 ) having an actuator chamber ( 2 ) and at least one pump chamber ( 4 ). The pump chamber ( 4 ) is provided with an inlet port and an outlet port. The pump chamber ( 4 ) is delimited by a displacement member ( 5 ) which is movable to and fro between a first position and a second position. The pump further comprises a movable actuator body ( 3 ), accommodated in the actuator chamber ( 2 ) and consisting of a magnetizable or magnetic material, for driving the displacement member ( 5 ). The pump also comprises magnetic drive means ( 8   a,    8   b ) for creating a magnetic field in order to move the actuator body ( 3 ). The actuator body ( 3 ) is freely movable relative to the displacement member ( 5 ) so that the displacement member ( 5 ) can be moved, by means of an impact motion of the actuator body ( 3 ), from the first to the second position.

[0001] A first aspect of the invention relates to a pump for pumping oneor more media, comprising:

[0002] a housing having an actuator chamber and at least one pumpchamber, which is provided with an inlet port and an outlet port andwhich is delimited by a displacement member which is movable to and frobetween a first position, in which the pump chamber has a maximumvolume, and a second position, in which the pump chamber has a minimumvolume,

[0003] a movable actuator body, accommodated in the actuator chamber andconsisting of a magnetizable or magnetic material, for driving thedisplacement member,

[0004] magnetic drive means for creating a magnetic field in order tomove the actuator body.

[0005] In U.S. Pat. No. 5,055,011 a pump is disclosed which is providedwith an electromagnet and a cylinder in which a piston is accommodatedas the displacement member. The piston is provided with a magneticelement. As a result of the magnetic element accommodated therein, thepiston can be moved in the cylinder by excitation of the electromagnet.

[0006] The object of the invention is to provide an improved pump.

[0007] To this end, the first aspect of the invention provides a pumpaccording to the preamble of claim 1, in which the actuator body isfreely movable relative to the displacement member so that thedisplacement member can be moved, by means of a impact motion of theactuator body, from the first to the second position.

[0008] With the magnetic drive means, a magnetic field can be generatedin the actuator chamber. The magnetic field can be applied such that theactuator body is accelerated in the direction of the at least one pumpchamber. The actuator body then impacts against the displacement member.Under the influence of the mass and velocity of the actuator body, thedisplacement member is moved from the first to the second position sothat the volume of the pump chamber is diminished and the medium to bepumped is pumped away through the outlet port of the pump chamber.

[0009] Preferably, electromagnetic drive means are used as the magneticdrive means. The electrical energy required to excite theelectromagnetic drive means is converted into kinetic energy by theactuator body. The kinetic energy is used to provide the energy foreffecting the pump stroke of the displacement member in the pumpchamber. Through continued excitation of the electromagnet during thepump stroke, the electromagnet also continues to supply energy to effectthe pump stroke.

[0010] In a preferred embodiment, the pump has two or more pumpchambers, the displacement member of each separate pump chamber beingable to be impacted against by the common actuator body. It is thuspossible to impact against the displacement members of the pump chambersalternately with the same actuator body. One advantage of this is that amedium can be pumped in a simple manner for each pump chamber, using asingle actuator body.

[0011] Preferably, the actuator body is movable from the one pumpchamber to the other pump chamber. By directing the actuator body fromthe one pump chamber to the other pump chamber, a multiple pumpmechanism is obtained, in which the energy is very efficiently used forthe pumping of media. Furthermore, by pumping a different medium foreach pump chamber, the pump according to the invention can be used as ametering pump, that quantity of a medium which is to be metered beingdetermined by the number of impacts multiplied by the pump chambervolume and being easy to regulate.

[0012] In a further embodiment, the electromagnetic drive means compriseelectromagnets fitted alongside the separate pump chambers. Thisconfiguration enables the actuator body to be easily repelled by anelectromagnet belonging to a pump chamber and attracted, for example, byan electromagnet belonging to another pump chamber.

[0013] A second aspect of the invention relates to a pump according toclaim 21. The pump according to this second aspect is provided withelectromagnetic drive means for creating a magnetic field in order tomove the actuator body and has a pump chamber which, at the inlet and/oroutlet port, is provided with a magnetically operable valve which isoperated by a magnetic field generated by the electromagnetic drivemeans, belonging to the pump chamber, for driving the actuator body.

[0014] It will be clear that the first aspect and the second aspect ofthe invention can also be used in combination.

[0015] Further embodiments and advantages of the invention will beexplained with reference to the drawing, in which:

[0016]FIG. 1 shows a diagrammatic view in cross section of an embodimentof a pump according to the invention,

[0017]FIG. 2a shows a top view of an actuator chamber of a pumpaccording to the invention with the actuator body in the middleposition,

[0018]FIG. 2b shows the actuator chamber of FIG. 2a with the actuatorbody in another position,

[0019]FIG. 3 shows an embodiment of a pump chamber of a pump accordingto the invention,

[0020]FIG. 4 shows another embodiment of a pump chamber of a pumpaccording to the invention,

[0021]FIG. 5 shows yet another embodiment of a pump chamber of a pumpaccording to the invention,

[0022]FIG. 6a shows an alternative embodiment of an electromagnet of thepump according to the invention,

[0023]FIG. 6b shows another alternative embodiment of an electromagnetof the pump according to the invention,

[0024]FIG. 7 shows an example of a magnetic non-return valve,

[0025]FIG. 8 shows an embodiment of the pump having a hydraulictransmission between the actuator body and the displacement member,

[0026]FIG. 9 shows an embodiment of the pump according to the inventionhaving electromagnets according to FIG. 6b,

[0027]FIG. 10 shows an alternative embodiment of an actuator body of apump according to the invention,

[0028]FIG. 11 shows an alternative embodiment of a pump chamber of apump according to the invention,

[0029]FIG. 12 shows a diagrammatic view in cross section of anembodiment of a pump according to the second aspect according to theinvention,

[0030]FIG. 13 shows in diagrammatic representation an embodiment of anon-return valve for the pump of FIG. 12, and

[0031]FIGS. 14a and 14 b show in diagrammatic representation anembodiment of a non-return valve for the pump of FIG. 12.

[0032]FIG. 1 shows a housing 1 having pump chambers 4 and an actuatorchamber 2. The pump chamber 4 has a movable wall 5, which at 6 ishinge-connected to the housing 1. The movable wall 5 is on one side ofthe housing more precisely denoted by 5 a and reproduces a firstposition, in which the pump chamber 4 has the maximum volume. On theopposite side, the movable wall 5 is denoted by 5 b and represents thesecond position, in which the pump chamber 4 has the minimum volume. Themovable wall 5 serves as a displacement member. Attached to the movablewall 5 is a permanent magnet 7.

[0033] In the actuator chamber 2 there is accommodated a single actuatorbody 3. In this example, the actuator body 3 is realized as a permanentmagnet, which is realized as a sliding body. In the example shown, thenorth pole of the actuator body 3 is situated at the outermost ends ofthe actuator body 3 and denoted by N. The south pole of the actuatorbody 3 is situated on the inner edge and is denoted by Z.

[0034] In addition, in the housing 1, electromagnets 8 a, 8 b arefitted. The electromagnets 8 a, 8 b have a soft iron core 9 with, roundabout it, a winding 11. The soft iron core 9 is connected to the arms10. The field lines of the electromagnets 8 a, 8 b shown result in aforce which is directed parallel to the plane of motion of the actuatorbody 3.

[0035] The actuator body 3 and the magnet 7 a, 7 b of the movable wall 5are oppositely polarized. As can be seen in FIG. 1, in this illustrativeembodiment that side of the magnet 7 a, 7 b which faces the actuatorbody 3 is the magnetic north pole, denoted by N. The magnet 7 a, 7 b ofthe movable wall 5 will thus always repel the actuator body 3. It isalso possible to polarize the magnet 7 a, 7 b in the same direction asthe actuator body 3, so that the movable wall 5 will attract theactuator body 3.

[0036] When the electromagnets 8 a, 8 b are not excited, the magnet 7 a,7 b will always be attracted by the soft iron core.

[0037] By excitation of the electromagnets 8 a, 8 b, the actuator body 3can be attracted or repelled. In FIG. 1, a situation is represented inwhich the actuator body 3 is located alongside a pump chamber 4 and itsassociated electromagnet 8 b. The electromagnet 8 b is now excited suchthat it repels the actuator body 3. At the same time, the electromagnet8 a is excited such that it attracts the actuator body 3. By virtue ofthe resultant force of the magnetic field generated by theelectromagnets 8 a, 8 b, the actuator body 3 is accelerated from theelectromagnet 8 b in the direction of the electromagnet 8 a. The pumpchamber which is located there has the movable wall 5 in the firstposition, that is to say has the maximum volume.

[0038] By virtue of its velocity and mass, the actuator body 3 movingtowards the pump chamber 4 will push the movable wall 5 from the firstto the second position, whereby the volume of the pump chamber 4 isreduced. A medium present in the pump chamber 4 will consequently bepumped via the outlet port (not shown in this figure) out of the pumpchamber 4.

[0039] The motion of the actuator body 3 is somewhat dampened close tothe movable wall 5 by the repellant effect of the oppositely polarizedmagnet 7 a.

[0040] If, in a non-illustrated alternative, the magnet 7 a, 7 b ispolarized in line with the actuator body 3, then whenever the actuatorbody 3 is repelled by an electromagnet 8, the displacement member (thewall 5) is repelled by the same electromagnet 8 and taken along by theactuator body 3. The displacement member is then moved from the secondto the first position.

[0041] The wall 5 with magnet 7 b remains in the second position as aresult of the attraction force of the electromagnet 8 b. When theelectromagnet 8 b, in a following excitation, is excited the other wayround in order thereby to attract the actuator body 3, the electromagnet8 b will also repel the magnet 7 b, whereby the movable wall 5 b ismoved from the second to the first position. The volume of the pumpchamber 4 is enlarged and medium will be drawn via an inlet port (notshown) into the pump chamber 4. The magnets 7 a and 7 b thus act asresetting means for the displacement member, which is here realized asthe movable walls 5 a, 5 b.

[0042] It is also possible to make the movable wall 5 a, 5 b itself outof a magnetic or magnetizable material, so that the wall 5 a, 5 b itselfreacts to the magnetic field generated by the neighbouringelectromagnet.

[0043] Good functioning of the pump can also be obtained by providingeach movable wall 5, instead of with the magnet 7 a, 7 b, with a spring(not shown). The spring pushes the movable wall 5 back from the secondposition to the first position after the actuator body 3 has beenremoved from the movable wall 5. The movable wall 5 can also itself berealized as a spring, for example a leaf spring.

[0044] Another possible embodiment is shown in FIG. 10. In this case,the pump chamber 4 is situated below or above the actuator chamber. Theactuator body 3 is provided with a cam 103. The free end of the movablewall 5 is provided with a protruding ring 104. When the actuator bodymoves up to the chamber 4, then the movable wall 5 stands obliquely(represented by a dotted line and denoted by 104 b). The cam 103 entersthe ring 104 substantially in the radial direction thereof, impactsagainst the ring and takes this along with it in its direction ofmotion. The cam 103 is then located in the ring 104. When the movablewall 5 comes into the second position (represented with a continuousline and denoted by 104 a), it will be unable to move any further. Whenthe actuator body 3 is moved away from the pump chamber 4, then the cam103 located in the ring 104 takes along the movable wall 5 in its motionfrom the second position to the first position, whereupon the pumpchamber volume is enlarged. The movable wall 5 tilts, whereby the ring104 also tilts to the point where the cam 103 is able to move back outof the ring 104.

[0045] In the pump chamber 4 a liquidtight bellows 12 can be fitted, asshown in FIG. 3. This bellows 12 is connected to an inlet port 13 and anoutlet port 14 of the pump chamber 4. Through the use of the bellows 12,a liquidtight circuit is obtained and no further sealing of the pumpchamber 4 is necessary, especially with respect to the actuator chamber2.

[0046] It is also possible to fit a liquidtight bellows with which thereis no movable wall but with which the bellows are impacted againstdirectly by the actuator body. This is represented in FIG. 11. Thebellows 212 is located in the actuator chamber 2 and forms, in fact, apump chamber 204. The wall of the bellows 212 acts as a displacementmember and is provided, on the side facing the actuator body 3, withmagnetic elements 207, which are polarized oppositely to the actuatorbody and have the same function as the magnets 7 a, 7 b in the exampleof FIG. 1, that is to say they act as resetting means.

[0047] The pump chamber 4 can also be realized differently, asrepresented in FIG. 4. The pump chamber 4 is realized as a cylinder inwhich a piston 25 can be moved to and fro. The inlet port and outletport of the pump chamber are denoted by 13 and 14 respectively. In thecase shown, the piston 25 has a piston rod 26. This piston rod 26 canextend into the actuator chamber 2 and can be impacted against by theactuator body 3.

[0048] In connection with possible damage to the media to be pumped,caused by the magnetic fields of the electromagnets, it may bedesirable, for example, for the pump chamber 4 to be distanced from theactuator chamber 2, as shown in FIG. 5. In this illustrative embodiment,a system of rods 27 forms a transmission, which transmits the impactmotion of the actuator body 3 to the piston 25, but it is clear thatother transmissions are also conceivable.

[0049] The pump chamber 4 can also be distanced from the actuatorchamber 2 through the use of a hydraulic transmission, as shown in FIG.8. In this case, a first chamber 40 filled with hydraulic fluid isdiminished in volume by a movable wall 50 being rotated about a hinge 60by means of the impact of the actuator body 3. The hydraulic fluid ispumped via a pipe 45 to a subchamber 4 a of the pump chamber 4. Thesubchamber 4 a of the pump chamber 4 is separated by a flexible membrane55 from a subchamber 4 b containing the medium to be pumped. When thesubchamber 4 a is filled with hydraulic fluid, then the membrane 55deforms and the medium to be pumped is forced out into the subchamber 4b and pumped away. In this example, the membrane 55 acts as thedisplacement member.

[0050] In FIG. 2a the actuator chamber 2 is represented with theactuator body 3 therein, the latter being realized as a radiallypolarized annular magnet. The actuator body 3 could also be realized asa disc-shaped magnet. Four electromagnets 8 a to 8 d are placed indiametrically opposing pairs round about the actuator chamber 2. Theactuator body 3 has in an associated plane of motion two degrees offreedom and can be directed to any desired position in the actuatorchamber 2. In the position shown in FIG. 2a, the actuator body 3 is inthe central position. This position can be maintained, for example, byexciting the electromagnets 8 a to 8 d in such a way that they repel theactuator body 3 with equal force.

[0051] In FIG. 2b the actuator body 3 is represented in the position inwhich the pump chamber 4 belonging to the electromagnet 8 b is served.From this position, the electromagnets 8 a to 8 d can be excited in sucha way that a magnetic field moves the actuator body 3 to the oppositepump chamber 4 alongside the electromagnet 8 a. It is also possible tomake the actuator body 3 move to one of the other pump chambersbelonging to the electromagnets 8 c, 8 d. This might be done in a directmotion, that is to say in a straight line, but this might also be done,if required, via the middle position shown in FIG. 2a, in order toobtain a sufficiently large velocity component in accordance with thedirection of motion of the displacement member in the pump chamber 4 tobe able to transfer sufficient kinetic energy to that displacementmember.

[0052] The actuator chamber 2 can be filled with a fluid havingapproximately the same specific weight as the actuator body 3. Theactuator body 3 can consequently be moved through the actuator chamber 2with virtually no friction.

[0053] The filling of the actuator chamber 2 with the fluid also offersthe possibility of making the actuator body 3 perform three-dimensionalmotions within the actuator chamber 2, independently of thegravitational force.

[0054] If the actuator chamber 2 is filled with a fluid, then anunderpressure can arise at the moment when the volume of the actuatorchamber 3 is enlarged by the reduction in the volume of the adjacentpump chamber. This can be compensated for by fitting in the actuatorchamber 3 an air chamber in open connection with the environment, theair chamber increasing in volume whenever an underpressure is present inthe actuator chamber 3. The volume increase is thereby compensated forand the underpressure abates.

[0055] With the embodiment shown in FIGS. 2a and 2 b, a plurality ofmedia, for example, could be pumped. It is also possible to use the pumpas a metering pump. This can be done by making the different pumpchambers 4 pump different media and by operating the displacementmembers of these pump chambers 4 in a certain order and in a certainnumber of pump motions. For instance, different media which have thusbeen controlled can be pumped and metered to form a desired mixture ofthese media. The number of pump chambers 4 and associated electromagnetsis not, of course, limited to four. More pump chambers 4 can also befitted around the actuator chamber 2. Given constant dimensions of thepump chambers and associated electromagnets, this number is onlylimited, in fact, by the dimensions of the actuator chamber 3.

[0056] In the previous illustrative embodiment the annular magnet isradially magnetized, but the actuator body 3 can also be realized as anaxially magnetized ring or disc, as represented diagrammatically in FIG.6a. The electromagnets 8 a to 8 d must then generate a field which isperpendicular to the direction of motion of the actuator body 3 in theactuator chamber 2.

[0057] In FIG. 6b an embodiment is shown in which the annular magnet isradially magnetized. The electromagnets 8 have a soft iron core 9, whichat one end 9 a adjoins the actuator chamber 3. In FIG. 9, an actuatorchamber 2 is shown with an actuator body 3 therein and provided withelectromagnets 8 round about, as shown in FIG. 6b. The ends 9 a of thesoft iron cores 9 lie alongside the actuator chamber 2. The other pole 9b is connected to a soft iron ring 19. When, in this configuration, twoelectromagnets 8 are oppositely excited, so that the one attracts theactuator body 3 and the other repels the actuator body, then the fieldlines are conducted via the soft iron ring 19 from the end 9 b of theone electromagnet 8 to the end 9 b of the other electromagnet.

[0058] The inlet or outlet port 13 and 14 respectively of the pumpchamber 4 is preferably provided with a non-return valve. This valve canbe a magnetically operated valve which can be opened and closed by theapplication of a magnetic field. This is preferably the magnetic fieldwhich is generated by the electromagnet 8 mounted alongside the pumpchamber 4 for the operation of the actuator body 3.

[0059] A non-return valve of this kind can be realized, for example, asshown in FIG. 7. From the pump chamber 4, fluid is pumped away via theoutlet port 14 and a valve chamber 31 to a discharge pipe 30. In thevalve chamber 31 there is a valve comprising an arm 32, which, at 35, ishinge-connected to the valve chamber 31. Attached to the free end of thearm 32 is a sealing body 33 for sealing the outlet port 14. In thesealing body 33 there is fitted a magnet 34, which reacts to themagnetic field of the electromagnet 8. During the pump stroke of thepump chamber 4, whereupon the electromagnet 8 is excited and thedisplacement member is moved from the first to the second position, themagnetic field of the electromagnet 8 pulls the magnet 34 away from theoutlet port 14 and opens the valve so that the medium is conductedthrough the discharge pipe 30. Preferably, the region around the seat ofthe valve is provided with a magnetic or magnetizable element 36. Thisensures that, when the electromagnet 8 is not excited, the sealing body33 is attracted by the seat and the valve is kept closed.

[0060] In FIG. 12 another pump 100 is shown, having a housing 101containing at least one pump chamber 102 provided with an inlet port 104and an outlet port 103. The pump chamber 102 is delimited by adisplacement member 105 in the form of a membrane connected to amagnetic element 106. The magnetic element 106 forms the actuator bodyof this pump 100 and has a north pole N and a south pole Z, as indicatedin the figure. The displacement member 105 is movable to and fro betweena first position, in which the pump chamber 102 has a maximum volume,and a second position, in which the pump chamber has a minimum volume.By “movable” is meant in this embodiment the convex or concavedeformation of the membrane 105.

[0061] The pump 100 further comprises magnetic drive means in the formof an electromagnet 107 for creating a magnetic field in order to movethe actuator body 106. The electromagnet 107 comprises a coil 107 a anda soft iron yoke 107 b. When, by the electromagnet 107, a field iscreated having a north pole N and a south pole Z, as indicated in FIG.12, then the actuator body 106 is attracted by the electromagnet 107 andthe membrane 105 will deform inwards, whereby the volume of the pumpchamber 102 is diminished. If the electromagnet 107 is excited the otherway round, then a reverse magnetic field is created, as indicated inFIG. 12, and the actuator body 106 is repelled, whereby the membrane 105is concavely deformed and the volume of the pump chamber 102 isenlarged.

[0062] The pump chamber 102 is provided at the inlet port 104 and outletport 103 with a valve 108, which is realized, for example, as a rubberflap which at one end 109 is fixed to the housing 101 and with the otherend 110 can move between the inlet port 104 or the outlet port 103. Thevalve 108 is provided with a magnet 109, which reacts to the magneticfield created by excitation of the electromagnet 107. The valve 108 thusreacts to a magnetic field generated by the electromagnetic drive means,belonging to the pump chamber 102, for driving the actuator body 106.The valve 108 seals the inlet 104 during the pumping stroke of thedisplacement body 105, thus as the volume of the pump chamber 102 isreduced. The valve 108 seals the outlet 103 during the suction stroke ofthe displacement body 105, thus as the volume of the pump chamber 102 isenlarged. The fact that the valve 108 is operated by the magnetic fieldapplied for the execution of a pumping stroke or a suction stroke meansthat the inlet port 104 and the outlet port 103 respectively are quicklyclosed once the end of the suction stroke and pumping strokerespectively is reached. Few pump losses are consequently incurred. Thisis especially favourable if the pump 100 is small in construction and isused to pump very small quantities of medium, as can be the case inmedical applications. A pump of this kind, by virtue of the very smallpump losses, allows for very accurate metering.

[0063] In FIG. 12, an inlet pipe 120 is connected to the inlet port 104,which inlet pipe is provided with a first non-return valve 121, which isrepresented diagrammatically. Connected to the outlet port 103 is anoutlet pipe 122, which is provided with a second non-return valve 123.The non-return valves 121 and 123 can be differently realized. Forexample, spring-pretensioned non-return valves can be used. Preferably,a magnetic resetting means is used. In FIG. 13, an example of anembodiment of such a non-return valve 121, 123 is representeddiagrammatically. The non-return valve 121, 123 comprises a valvehousing 124 having a valve inlet 128 and a valve outlet 129.

[0064] In the valve housing 124 there is accommodated a magnetic closingmember 126, which in the closed state of the valve bears against a valveseat 125. The closing member 126 has a north pole N and a south pole Z,as indicated in the figure. Attached to the valve housing 124 is apermanent magnet 130, which is polarized in such a way that this repelsthe closing member 126 in the direction of the valve seat 125. Thedistance x between the closing member 126 and the magnet 130 determinesthe force with which the magnet 130 repels the closing member 126 andhence the pretension with which the closing member 126 is pressedagainst the seat 125.

[0065] The pressure of a medium current through the valve inlet 128 mustovercome the pretension in order to open the valve. By making thedistance x adjustable, the pretension with which the valve is held inthe sealed state is also adjustable.

[0066] In FIG. 14, a system of non-return valves 130 for the inlet pipe120 and the outlet pipe 122 is shown. The valve system 130 comprises thefirst non-return valve 121 and the second non-return valve 123. Theclosing members 126 of the first non-return valve 121 and the secondnon-return valve 123 are polarized in such a way and the firstnon-return valve 121 and the second non-return valve 123 are positionedone relative to the other in such a way that the closing members 126repel each other and are thus each pressed with the same pretensionagainst their associated valve seat 125. In this illustrativeembodiment, the first non-return valve 121 and the second non-returnvalve 123 are thus pretensioned by the same magnetic resetting meanscomprising two closing members 126.

[0067] The first non-return valve 121 and the second non-return valve123 can be placed one against the other, as shown in FIG. 14a, thepretension of both valves being maximal. By placing the non-returnvalves 121 and 123 at a distance y apart, as shown in FIG. 14b, thepretension can be reduced. By making the distance y adjustable, thepretension of the valves 121, 123 can be made adjustable.

[0068] The valves 121, 123, in the form as shown in FIG. 14, have thesame pretension. If, for the first non-return valve 121, a lowerpretension is desired than for the second non-return valve 123, then anelement made of magnetic or magnetizable material, for example, can befitted alongside the seat 125 of the first non-return valve 121, so thatthe closing member 126 is attracted and the pretension is reduced.

[0069] It should be noted that in FIG. 12 a non-limiting example isgiven of a pump according to the second aspect of the invention. It willbe clear, for example, that a pump according to the first aspect of theinvention, which is provided with a valve 32 as shown in FIG. 7, shouldalso be regarded as an example of a pump according to the second aspectof the invention.

1-27. (canceled)
 28. Pump for pumping one or more media, comprising: ahousing having at least one pump chamber, which is provided with a portand which is delimited by a displacement member which is movable to andfro between a first position and a second position, a movable actuatorbody, consisting of a magnetizable or magnetic material, for driving thedisplacement member, electromagnetic drive means for creating a magneticfield in order to move the actuator body, wherein the pump chamber, atthe port, is provided with a magnetically operable valve which reacts tosaid magnetic field generated by the electromagnetic drive means, suchthat when the displacement member is driven from the first position tothe second position, the magnetically operable valve at the port isdriven by the magnetic field to a position in which the port is closed,and when the displacement member is driven from the second position tothe first position, the magnetically operable valve at the inlet isdriven by the magnetic field to a position in which the port is opened.29. Pump according to claim 1, wherein the magnetically operable valveis provided at an inlet port of the pump chamber.
 30. Pump according toclaim 1, wherein the magnetically operable valve is provided at anoutlet port of the pump chamber.
 31. Pump according to claim 1, whereinone common magnetically operable valve is provided at an inlet and anoutlet of the pump chamber.
 32. Pump according to claim 1, wherein thepump chamber has an inlet port and an inlet pipe is connected to saidinlet port, which inlet pipe is provided with a first non-return valve.33. Pump according to claim 5, in which the first non-return valve isprovided with a magnetic resetting means in order to keep the firstnon-return valve under pretension in a closed state.
 34. Pump accordingto claim 5, wherein the pretension of the magnetic resetting means isadjustable.
 35. Pump according to one of claims 1, wherein the pumpchamber has an outlet port and an outlet pipe is connected to saidoutlet port, which outlet pipe is provided with a second non-returnvalve.
 36. Pump according to claim 8, wherein the second non-returnvalve in the outlet pipe is provided with a magnetic resetting means inorder to keep the second non-return valve under pretension in a closedstate.
 37. Pump according to claim 9, wherein both the first non-returnvalve and the second non-return valve are pretensioned by the samemagnetic resetting means.
 38. Pump according to claim 1, wherein theactuator body is freely movable relative to the displacement member sothat the displacement member can be moved, by means of a impact motionof the actuator body, from the first to the second position.